1. Field of the Invention
The present invention relates to a plasma process apparatus.
2. Related Art
With the increase in chip size of a DRAM, an MPU and the like, a silicon substrate to be used as their base body trends to be made larger in diameter. Although a process of etching an oxide film or a polysilicon material is one of the most important processes in production of semiconductor devices, an ordinary RIE apparatus of parallel plate type which has been used up to now cannot meet a plasma performance required for processing a fine pattern of 1.0 m or less (for example, a process pressure of 50 m Torr or less, an ion current density of 1 mA/cm2, and an electron density of 1xc3x9710 cmxe2x88x923 or more).
In order to solve this problem, a plasma source having a magnetic field introduced into it has been developed and a magnetron plasma etching apparatus using a dipole ring magnet (hereinafter referred as to DRM) has been publicized as an example of an apparatus provided with such a plasma source (see Japanese Patent Laid-Open Publication No. Hei 6-37,056).
However, the above-mentioned magnetron plasma etching apparatus using a DRM can generate a low-pressure and high density plasma but has a problem that it is difficult to precisely control a plasma generated on a substrate body. That is to say, introducing a horizontal magnetic field onto a substrate body has made it difficult to uniformalize a plasma density on a substrate and uniformalize a self-bias voltage. At the present time, a solution of uniformalizing a plasma density by sloping a magnetic field (Japanese Patent Laid-Open Publication No.Sho 62-21,062) or by turning a magnetic field introduced into a process space (Japanese Patent Laid-Open Publication No.Sho 61-208,223) has been proposed.
However, a solution by a technique according to Japanese Patent Laid-Open Publication No.Sho 62-21,062 has a problem that the optimum value of a sloping magnetic field is varied in case of changing a process pressure or the like. On the other hand, a solution by a technique according to Japanese Patent Laid-Open Publication No.Sho 61-208,223 has a problem that a plasma generated on a substrate body in process is seemingly uniformalized but a mechanism for turning a magnetic field and it is difficult to make a plasma process apparatus small in size as a whole.
In order to solve these problems, a solution technique of uniformalizing a plasma in a uniform horizontal magnetic field by applying a high-frequency electric power to an auxiliary electrode has been disclosed. This technique can uniformalize a plasma by changing a high-frequency power to be applied to an auxiliary electrode even in case of changing a process pressure or the like, and can make a plasma process apparatus small in size since it is not necessary to turn a magnetic field. However, it is necessary to make the distance between a substrate body and the upper electrode be 30 mm or more so as to keep a pressure distribution within a few percents in a plasma process apparatus for processing a substrate body of 300 mm or more in diameter. Since an effect of applying a high-frequency power to an auxiliary electrode does not reach a substrate body at such a distance, it is difficult to uniformalize a plasma.
An object of the invention is to provide a plasma etching apparatus being capable of uniformalizing the density of a plasma generated on the surface of a substrate body and the self-bias voltage as keeping uniform, the pressure distribution on the substrate body without turning a means for applying a magnetic field and being capable of performing a uniform etching process without a charge-up damage, and provide a, sputtering apparatus being capable of performing a uniform sputtering process generating no stress on a substrate body.
A plasma process apparatus according to the present invention is characterized by a plasma process apparatus provided with two electrodes I and II of parallel plate type and a magnetic field applying means for applying a magnetic field being horizontal and one-directional to a surface which a plasma process is performed onto, wherein an auxiliary electrode is provided around the periphery of one of the two electrodes, a space where a plasma can be excited is provided at the opposite side of said auxiliary electrode to the face facing the other electrode, and a means for applying a high-frequency power to said auxiliary electrode is provided.
According to the present invention, it is possible to. uniformalize the density of a plasma generated on the surface of a substrate body and uniformalize the self-bias voltage as keeping uniform the pressure distribution on the substrate body without turning a magnetic field, and implement a plasma etching process capable of performing a uniform etching process without a charge-up damage on the substrate body and a uniform sputtering film forming process generating no stress on the substrate body.